Devices communicate or exchange data with other devices using a number of different communication interfaces. Hard-wired communication interfaces include serial and universal serial bus (USB). Wireless communication interfaces include Bluetooth, wireless Ethernet (also called WiFi or 802.11b), and general packet radio service (GPRS) to name a few.
Bluetooth is a low power wireless personal area network (PAN) intended for short distance communications and intended to be used as a cable replacement. Bluetooth is commonly used for applications such as wireless headsets, wireless synchronization of personal digital assistants (PDAs) with computers, and wireless printers and keyboards.
WiFi is wireless Ethernet local area network (LAN) based on IEEE (Institute of Electrical and Electronics Engineers) standard 802.11b. Both WiFi and Bluetooth operate in the 2.4 gigahertz (GHz) band. This band is 83.5 megahertz (MHz) wide, beginning at 2.4 GHz and ending at 2.4835 GHz. WiFi only occupies about a quarter of the 83.5 MHz bandwidth that is available in the 2.4 GHz band. 802.11b defines eleven possible channels in the 2.4 GHz band.
In contrast to WiFi, the Bluetooth channel does not utilize a fixed frequency but rather employs frequency hopping. Bluetooth devices hop among seventy-nine defined frequency channels in the 2.4 GHz band. In this way, Bluetooth occupies the entire 2.4 GHz band but, at any instant in time, only occupies a small portion of the band. Bluetooth hops to a new channel in the 2.4 GHz band about 1,600 times a second.
GPRS is a packet-based wireless communication service which operates on cellular telephone networks.
Some devices use only one communication interface. This one interface may be one of the hard-wired interfaces listed above or may be one of the wireless interfaces listed above. Devices that use only one communication interface can therefore only communicate with other devices using that same interface. As the number of communications interfaces increases, it is less likely that a device with only one communication interface will be able to communicate with other devices.
To address the problems associated with devices having only one communication interface, some devices now include two or more communication interfaces. While these devices with two or more communication interfaces are able to communicate with a larger number of other devices, the existence of multiple communication interfaces in the same device creates other problems. A device with two or more communication interfaces may receive data through more than one interface simultaneously and must be able to process any data that is simultaneously received through more than one interface.
Additionally, the close proximity of transmitters for the multiple wireless communication interfaces can cause interference when two or more transmitters are transmitting simultaneously. This interference problem is especially acute when the multiple wireless communication interfaces utilize the same communication frequency band. For example, as discussed above, Bluetooth and WiFi both communicate in the 2.4 GHz band. If a device is sending data via a WiFi interface at a certain frequency in the 2.4 GHz band and the device also attempts to simultaneously send data via a Bluetooth interface, it is possible the Bluetooth interface may hop to the same frequency that the WiFi interface is using and transmit at that frequency. This resulting interference will cause the WiFi interface to abort sending its data. After aborting its attempt to send data, the WiFi interface will then reattempt sending its data at a lower data rate. As a result, communication speeds decrease and network performance is degraded.
Bluetooth version 1.2 addresses the issue of interference with WiFi using a technique called adaptive frequency hopping. Adaptive frequency hopping changes the channel map used by Bluetooth when it senses data collisions. However, this method does not prevent collisions but rather responds to collisions. Therefore this technique also results in decreased communication speeds.
As such, there is a need for a device that is capable of simultaneous communication over multiple wired and wireless networks, such that the device is capable of processing data received simultaneously over multiple networks and such that the device is capable of preventing interference when communicating over multiple wireless networks in the same frequency band.